The Insane Scientist
by TheBlackSeaReaper
Summary: Fem!Harry. Mayuri was with the group of soul reapers that were turned vizards, but he  was killed by Aizen. 115 years later he was reborned as Jessica Potter. No pairings.
1. Chapter 1

**The Insane Scientist**

**Chapter One**

Summary: What if Mayuri Kurotsuchi went with the others that night that Aizen preformed his sick experiments and was killed? After a hundred and fifteen years later (?) Mayuri was reborn as Jessica Potter. With his or her past memories, Jessica began experimenting on herself to improve her body. Also later on people's pets at Hogwarts. Disclaimer: I own nothing. I wished that I did, but sadly I don't.

It was the summer after Jessica's fourth year and it could be simply said that everyone was nuts. Her twin brother, Evans Potter had witnessed the Dark Lord's return just last year. And now because of that, they had to stay at Hogwarts for the summer. Mayuri was caught between being pleased with the results of staying at Hogwarts or angry because of the change of plans that she as usual was not informed of until the last minute.

It was always like this for Mayuri to be ignored by the Potter family and her so called godfather, Sirius Black. She did not complain as she figured it could be worse with a family that always demanded her attention and time away from her experiments, like just recently, she replaced her ears with a weapon that she could use in case she was corned and did not have her wand with her. Everyone believes that Evans Potter was the Chosen One or from what she heard the Child of Prophecy. She had bugged the Great Hall where the meetings take place now in summer and she can watched them from her huge computer inside her trunk.

When Mayuri first got the trunk from her parents who seemed to be not too happy with her going to Hogwarts with Evans. She had to improve it and make it better, so with a bunch of runes, she was able to make it into multiple rooms like a mansion. Then she began building her computer that runs off of magic to store any data that she had collected. Just last year, she had finally created Nemu Kurotsuchi, her daughter, who turned out to be a great help to her whenever she was off in classes. She would never admitted even if it will save her soul from hell. But Nemu stays inside the trunk no matter what; Mayuri will not take the chance of her being discovered.

Mayuri Kurotsuchi also known as Jessica Potter was 5'5' and still growing. She had her long black hair tied back so it could not get in her way when she experiments and also to hide what she did to her ears, so no one could make a fuss over what she had done to them. She also painted her fingernails blue and on her right hand, she grew her fingernail on her middle finger, five inches. People and her family thought she was weird, but Mayuri never really cared about that at all. To her, they were experiments waiting for her to get to them. She knew that she could not do that as the Soul Society might find out about her and her projects. Mayuri had to wonder what ever happen with Aizen and his two kiddies that was with him that night. She personally would like to get them onto her table and dissect them and see what makes them tick.

**(Scene Break)**

"There you are, Jessica. I was looking everywhere for you," Lily said as she saw that her daughter came into the Great Hall for breakfast.

"No wonder you could not find me, I was taking a shower before coming down here. It's a normal thing to do in the morning, is it not?" Mayuri asked her, honesty her life would be a whole lot better if Lily Potter was not in it.

"Don't be rude to your mother, Jessica Potter," James snapped at his daughter.

"I was just simply answering her question. No need to snap at me, Potter," Mayuri sneered as she got up with a plate full of food and began walking out.

"Where are you going, Jessica? Can't you sit here with your family and spend some time with us?" Lily asked as she saw that her daughter was going to walk out again with a plate full of food.

Mayuri stopped and said, "I am going to do something worth my time. I don't really like it if I waste it. And besides, you don't need me; you got Evans to spend time with."

The others in the Great Hall just watched as Mayuri walked out of the hall. They all don't know what to make of her and they all knew that they did not know much about her. Jessica Potter has no friends and made no effort make any, although Luna Lovegood did sometimes hung out with her. She was never friendly or nice to anyone and everyone made an effort to keep out of her way. Only place that anyone may find her was in the library, pouring over books and making notes. She was the top student in every class. And she can make a seventh year cry like a five year. And another thing to note was that ever since she first started Hogwarts, pets like Mrs. Norris went missing, even Fluffy, Hagrid's three headed dog. Snape still believes to this day that Jessica Potter is responsible for their disappearances, but no one really wants to believe him.

"I just wish that I could get to know our daughter and spend some time with her. That's all," Lily begins to cry.

"I know, sweetie. Everything will be okay, she just needs some time to get use to us wanting her around," James said as he tries to comfort her as best as he could.

Snape even snorted and said, "I really doubt that will ever happen. I believe that Miss Potter made the choice to be anti-social on her own. You know, sometimes whenever I have her in my class, she gets this craze look in her eyes whenever she works on the potion that I assign them at that time. I think that she is beyond our help."

"What do you mean that she is beyond our help, Snape?" Sirius questioned him. Sirius was Jessica's godfather, but he was never that person to her. He always spent time with her younger twin, Evans when they were younger. Now after what happened last year, he seriously regretted his action and what they have done to Jessica.

"What Severus means is that Jessica Potter is an insane researcher and a mad scientist all rolled into one. I watched her myself on several occasions without her knowing it and just last year, she was able to create something that looks, acts, and has all of the functions of a human being. It's a pity that Jessica must keep her locked up in that trunk of her. But as I was saying, Jessica Potter is the type of person that is driven to gain knowledge, but unlike Tom Riddle who would use that knowledge to do evil things to other people, she just wants to know. But she would do anything to gain that knowledge," Headmaster Dumbledore explained to the others.

"We also forgot to mention to her that an old friend of mine is sending some people that can help up with defeating Tom," The Headmaster said.

**(Scene Break)**

"Nemu, has there been any more blasts of spiritual pressure in Japan lately?" Mayuri asked as she ate her share of the food that she brought with her while leaving the rest for Nemu.

"No, but I did find out something important," Nemu said.

"Well, what is it? Answer me, I don't have all day you know," Mayuri snapped at Nemu.

"Headmaster Dumbledore knows about me and that you created me." Nemu answered.

"WHAT! Show me, now!" Mayuri shouted as Nemu pressed in some keys on the computer keyboard.

_Snape even snorted and said, "I really doubt that will ever happen. I believe that Miss Potter made the choice to be anti-social on her own. You know, sometimes whenever I have her in my class, she gets this craze look in her eyes whenever she works on the potion that I assign them at that time. I think that she is beyond our help." _

"_What do you mean that she is beyond our help, Snape?" Sirius questioned him. Sirius was Jessica's godfather, but he was never that person to her. He always spent time with her younger twin, Evans when they were younger. Now after what happened last year, he seriously regretted his action and what they have done to Jessica._

"_What Severus means is that Jessica Potter is an insane researcher and a mad scientist all rolled into one. I watched her myself on several occasions without her knowing it and just last year, she was able to create something that looks, acts, and has all of the functions of a human being. It's a pity that Jessica must keep her locked up in that trunk of her. But as I was saying, Jessica Potter is the type of person that is driven to gain knowledge, but unlike Tom Riddle who would use that knowledge to do evil things to other people, she just wants to know. But she would do anything to gain that knowledge," Headmaster Dumbledore explained to the others._

"_We also forgot to mention to her that an old friend of mine is sending some people that can help up with defeating Tom," The Headmaster said._

"HOW DARE HE! Spying on me. I just can't believe I did not even notice that. Well, I will solve that just in case he did that again," Mayuri ranted to Nemu as she began thinking of ways to make sure that she could find the Headmaster no matter where he is.

Without turning around, Mayuri said to Nemu, "Since the Headmaster knows about you and told everyone about you, Nemu, for now on you will be accompanying me everywhere, unless I tell you other wise. Understand?"

"Yes, Mother," Nemu said to Mayuri before getting something that Mayuri needed.

_I wonder who are those friends of the old coot who are coming. I hope that they won't get in my way_, Mayuri thought to her self.

**(Scene Break)**

The Headmaster stopped in front of Jessica's trunk and called out, "Jessica, I would like for you to come to my office to talk about some things right now and please bring that young woman that you created with you. I will like to meet her. Oh, I hope that you like lemon drops."

The Headmaster only had to wait less than a minute before the trunk lid opened and out step Jessica and the young woman. Jessica had a look on her face that basically said that what he wants to talk about better be good or else someone is going to suffer. A lot.

"Good, please follow me," Headmaster Dumbledore told them.

**(Scene Break)**

"Now that we are all comfy. Is there anything that you two would like to drink or eat before we get started?" Dumbledore asked.

"No, just get to the point, you old coot!" Mayuri snapped at him. Mayuri was angry that someone had the nerve to pull her away from her project.

"Very well then," Headmaster Dumbledore said as he studied Mayuri carefully. "Miss Potter, what do you know of the Soul Society?"

Mayuri froze as she did not expect that question, anything but that question. Mayuri's mouth was wide opened and it seemed that her eyes would pop out of her head.

"I take it from your expression that is on your face that you do know what I'm talking about. Tell me, did you stumble on the information in a book or were you reincarnated with your memories intact?" Headmaster Dumbledore asked as he was now very curious about Jessica Potter. If she was reincarnated with all of her memories intact, it will explain a lot of things about her.

**AN: I hope that you all like it. This story just popped into my head and refused to get out until I wrote it down. To make a few things clear, Mayuri was reborn as a girl, will not be abusive towards Nemu, and a little less crazy than before. The next chapter will be the confession of Mayuri and she will tell Dumbledore about her past life. Oh, before I forget Mayuri is also known as Jessica Potter. Please review and tell me what you all think of it. Have a nice day, everyone.**


	2. Chapter 2

**Chapter 2**

Disclaimer: I own nothing of Harry Potter or Bleach. I wished that I did, but sadly I don't. So don't sue me as I am really not worth that type of effort. Just please read my chapter and story and then review.

"Talking in English"

"_Talking in Japanese"_

_**(Scene Break) **_

"So you figured it out, you miserable old coot. I wonder how though, was it from our past debates or did someone tell you?" Mayuri asked as she wondered how this was found out about her.

Dumbledore chuckled as he said, "I find very refreshing that someone is brave enough to insult me like you do. To answer your question, yes, our past debates did clue me in as no student that I ever came across had as much knowledge as you did, not even myself or Tom Riddle at your age. My friend, Yamamoto, explained to me about reincarnations and when I described you, Yamamoto told me who you really are, Mayuri Kurotsuchi."

Mayuri stared at Dumbledore as she snapped at him, "Its times like these that I wished that I could knock you unconscious, drag you to my lab, and then pick your brain for every piece of information that you may have stored inside of there."

That statement caused Dumbledore to laugh out loud. That was another thing that he liked about Mayuri and that was she would tell a person what she thought of them without holding back in fear of sounding rude or mean.

"So you know Head Captain Yamamoto then, damn," Mayuri snapped. Nemu held out her hand as if she was wanting something and Mayuri dug around in her pocket and gave Nemu fifteen galleons.

Dumbledore raised an eyebrow at the exchange of money that happened in front of him. He was wondering what had just happened, maybe Mayuri and her daughter made a bet on something that involved him in some way.

"I hope that you are happy, you crazy geezer. Thanks to you knowing the Head Captain, I lost fifteen galleons. I can't believe that my daughter got one up on me," Mayuri muttered the last part.

But before anyone could say anything or do anything, a house elf popped in and told the Headmaster that his visitors were here and waiting for him in the Great Hall.

"Well, Jessica, I believe that our visitors are here and why don't you bring Nemu with you. I am sure that you will be happy with them," The Headmaster stated as he got up from the chair behind his desk and made his way to the door. He motion for Mayuri and Nemu to follow him.

"I will see about that," Mayuri snapped. The Headmaster was too damn happy and Mayuri did not trust that nothing good would come out of that.

_**(Scene Break)**_

Mayuri stepped inside the Great Hall and stopped short as there were soul reapers standing there waiting patently for the Headmaster to arrive. They were not some low leveled unknown soul reapers, no; they were made up of captains and vice captains. However, one soul reaper caught her eye; it was Kisuke, her former Captain and Head of the Department of Research and Development. But he was not in his uniform as the others. It was probably a good thing that Aizen was not there or she would have attacked him and dragged him into her lab and make him into one of her test subjects.

Kisuke looked over to where the Headmaster walked in and spotted two people following him. One was a teenage girl who was around the age of fourteen and the other looked to be in her prime at the age of eighteen. But the younger one seemed to be very familiar to him. Looking closer, he caught a glimpse of the cones that were where the ears should have been, the blue colored nails and the long one, and last but not least, the calculating look in her eyes. It was Mayuri Kurotsuchi and he was reborn as a girl.

Kisuke began to laugh like a mad man that he was and was pointing to Mayuri as he was laughing. The other soul reapers turned to Kisuke and were confused on why he was laughing like a hyena. Looking in the direction where Kisuke was pointing caused them to blink a few times before focusing on the girl.

Shunsui blinked and then said in a stunned voice, _"I do not believe it. Its Mayuri Kurotsuchi. Wow! I would not have believe that you make a beautiful lady. And who is this beauty standing behind you?"_

Mayuri screeched at him, _"Believe it, you baka! And stay away from my daughter, you blasted pervert!"_

That shut up both Kisuke and Shunsui and they openly gaped and looked back and forth from Mayuri and then Nemu. Kisuke used shunpo to appear in front of Nemu and he began to examine Nemu by walking around her and looking at her closely.

Turning to Mayuri, he questioned, _"A mod soul in Gigia (?)?"_

Mayuri suddenly turned in to a business person or a Professor as she explained Nemu and all that she can do and how she was able to make Nemu. She explained how Nemu can function and all of that stuff to Kisuke. But since the Potters and the rest of the Order were there, she said all of this in Japanese, so they would not understand what she was saying.

"_Who is this and how do you guys know her!"_ A red head with tribal tattoos demanded as he looked between his Captain and Mayuri.

Mayuri recognized the Captain as Byakuya Kuchiki. Mayuri almost did not recognized him, but it seems that Kuchiki had finally gotten control over his annoying tempter of his.

Byakuya was the one to answer the vice Captain, _"Renji, this is the infamous Mayuri Kurotsuchi, the vice president of the Department of Research and Development. Mayuri was well known for his habit of wanting everyone to be his test subject. About 110 years ago, Mayuri was the only one killed by the traitor Aizen while the rest were turned into vizards. Apparently, Mayuri is reincarnated as Jessica Potter. On a side note, Mayuri Kurotsuchi was a former inhabitant of the Maggot's Nest. So if I were you, I would not make her angry."_

The vice Captain Renji was stunned to see Mayuri looking at him like he was nothing but a bug to her.

"What the hell is going on! What are you talking about! As the Boy –Who –Lived, I demand to know!" Evans demanded angry. He was mad that the so called soul reapers were ignoring him and focusing on his good for nothing twin.

Renji was the first to snapped back at him, "We do not have to say anything to you, human."

Lily Potter set in front of Evans and demanded, "Apologize to my son! If it was not for him, you will be all killed by the Dark Lord!"

Mayuri stepped forward and sneered at her, "Shut up, you stupid woman! How can they be killed by some weak fool like that thing when they are already dead! They are called soul reapers for a reason! Use your brain for once and think, woman!"

"Don't you dare talk to your mother like that!" James went a little too far and slapped Mayuri in the face.

Mayuri spat out some blood and then began to rip and tear into James.

"MOTHER! HA! Like I would call some one like her mother! No normal mother would ignore one child in favor of another! If I remember correctly that you two were angry that I got into Hogwarts as your precious baby boy. Who I should point out that he is nothing but a weak, whining, fat, stupid, good for nothing except maybe the possibility of being used as a meat shield, brat. Open your eyes, you blasted fool, and look around. Almost every single student and Professor hates your son as he never does his homework, copies off of others or bullies someone else into doing it for him. The only talent that he has is for that blasted game Quidditch! And if you had remembered that you two had another child, you would have noticed that I have been living on my own since I first got that letter!" Mayuri screeched at James.

Lily, James, and Evans had their mouths opened and was staring at Mayuri like she had grown a second head. Suddenly, clapping was heard and Mayuri looked around to see who was clapping. It was Severus Snape and he had a smug look and a smirk on his face.

**AN: I hope that you all like this chapter. Please review and tell me what you all think of it. Have a nice day, everyone.**


	3. Chapter 3: Information Revealed

**The Insane Scientist**

**Chapter 3: Information Revealed**

Disclaimer: I own nothing of Bleach or of Harry Potter. I really wished that I did, but sadly I do not. I just want to say 'Thank you' to all of those who wrote a review, favored, and or followed this or any of my other stories, it means a lot to us authors to have your support and it also encourages us to write more.

"Talking"

'_Thinking'_

"_Speaking in Japanese"_

**(Scene Break)**

_Last time…_

_Lily Potter set in front of Evans and demanded, "Apologize to my son! If it was not for him, you will be all killed by the Dark Lord!"_

_Mayuri stepped forward and sneered at her, "Shut up, you stupid woman! How can they be killed by some weak fool like that thing when they are already dead!? They are called soul reapers for a reason! Use your brain for once and think, woman!"_

"_Don't you dare talk to your mother like that!" James went a little too far and slapped Mayuri in the face._

_Mayuri spat out some blood and then began to rip and tear into James. _

"_MOTHER! HA! Like I would call some one like her mother! No normal mother would ignore one child in favor of another! If I remember correctly that you two were angry that I got into Hogwarts as your precious baby boy. Who I should point out that he is nothing but a weak, whining, fat, stupid, good for nothing except maybe the possibility of being used as a meat shield, brat. Open your eyes, you blasted fool, and look around. Almost every single student and Professor hates your son as he never does his homework, copies off of others or bullies someone else into doing it for him. The only talent that he has is for that blasted game Quidditch! And if you had remembered that you two had another child, you would have noticed that I have been living on my own since I first got that letter!" Mayuri screeched at James._

_Lily, James, and Evans had their mouths opened and was staring at Mayuri like she had grown a second head. Suddenly, clapping was heard and Mayuri looked around to see who was clapping. It was Severus Snape and he had a smug look and a smirk on his face._

**(Scene Break)**

After Mayuri had really told the two adult Potters what she really thought of them and also revealed some shocking, yet not so shocking news about Evans and his time at Hogwarts. Out of the corner of her eye, Mayuri could see that Mrs. Weasley was getting ready to scold her off and destroy her hearing at the same time. But Headmaster Dumbledore stepped up and put a stop to it, before anything could happen.

"Miss Potter, why don't you take us to that amazing room that is in your trunk?" Albus asked in a gentle tone, yet it really meant that she did not have a choice in the matter as it was really a command.

Mayuri glared at the Headmaster as she demanded angrily, "Who is 'us'?"

Albus simply smiled and answered her cheerfully, "Myself, our guests, Professor Snape, Professor McGonagall, and Moody."

"Fine," Mayuri snapped. "I guess that I don't really have a say in this, since you could kick me out of Hogwarts at anytime. Come Nemu!"

The soul reapers and the four members of the Order followed the now fifteen year girl and her daughter out of the Great Hall.

**(Scene Break)**

_Inside Mayuri's Trunk…_

"Don't touch anything, you fools!" Mayuri yelled at the group, who were looking around in awe and wonder.

As Mayuri turned on the computer and Kisuke began asking questions about the computer as the other soul reapers listened in interest, Professor Snape turned to Albus and quietly asked, "Why are we even here? Potter does not know anything about the Dark Lord."

Both Professor McGonagall and Moody nodded their heads as they agreed with Professor Snape for once in their long lives. They really don't believe that a fifteen year old would know anything about what they knew or were doing.

Albus just chuckled as his eyes began to twinkle even more. Albus stated, "That is where you are wrong, my dear boy. Jessica knows more about the Dark Lord than we do. She even can spy on anyone of us, including what takes place inside my office, without even leaving her trunk."

"Impossible!" Exclaimed all three of them at the same time.

A voice pulled their attentions away from the Headmaster to the giant computer screen that showed at least twenty different places in Hogwarts at the same time, including their offices and the Great Hall. Mayuri told them in a smug tone, "Nothing is really impossible to do. Its just your simple brains can't work at this level, and that leaves you just one step about the thinking level of monkeys."

The two professors and Moody just stared at the screen in shock, not knowing what to say or how to respond to the insult due to the shock. Meanwhile, Albus just asked, "Jessica, what do you know about Voldemort?"

Now this gained everyone's attention as Nemu began pulling up information on the Dark Lord while Mayuri began to speak, "Tom Marvolo Riddle also known as Lord Voldemort is simply an idiot to begin with. Sure his brain level is just two steps below Dumbledore's, but way above yours."

Nemu had pulled up a map of Great Britain on the screen with a lot of moving dots that were different colors. There were more fifteen red dots, and at least fifty green dots, and four black dots.

Mayuri began to explain, "On the map are red and green and black dots. The red dots pinpoint all of the locations that contain the Dark Lord's magical signature, which he foolishly left behind. That stupid baboon! The green dots are the location of his death eaters that bare his Dark Mark."

Kisuke interrupted by asking, "The black dots, there are only four, but we were told that there are eight."

Mayuri turned to Nemu and demanded, "Nemu, retrieve the three items immediately. Hurry up!"

Albus and the other soul reapers finally got an understanding what those black dots represented, while the other three had not idea what was going on, but they had a feeling that whatever it was, it was very important and most likely dangerous.

Moody finally had enough of not knowing what was being talked about, so he asked, "Would someone tell us, who don't know what's going on around here, what you all are talking about?"

"How rude," Mayuri sneered as Nemu came back with three items: a locket, a black book, and a tiara. Only the black book showed any damaged. "Tell me, do you have any idea what a Horcrux means?"

Moody blinked and said, "I have heard of that word before, but never really understood what it really meant."

Professor Snape and Professor McGonagall both shook their heads as they never heard the word before, but judging the expressions on the Headmaster's and the soul reapers' faces told them that it's a very bad thing.

Shunsui walked closer to the items and began really studying them carefully and he stated, "I was really hoping that the information was wrong. Not even Aizen would do something like this."

Mayuri looked to the three, who don't know what a Horcrux was and she began explaining it to them, "A Horcrux is basically a soul fragment stored in a trophy or a container. The Dark Lord ripped his soul into fragments and put them into different item. He was able to do this through cold blooded murder and a ritual. In his mind, if he did this, he would obtain immortality and never see death, which is his greatest fear. Even Hollows would try and destroy him if they ever found this out. What all the others who did this same sinful act were killed. And their souls were wiped out of existence. So its only a matter of time before Tom meets the same fate."

Moody, Professor Snape, and Professor McGonagall were all white as paper. They, especially Snape, knew that they should not be so shocked that the Dark Lord did this, yet they were shocked. They could not get over the fact that anyone would do something this horrible to their own soul.

Moody seemed to be able to shake himself out of shock, and with a glare that would scare anyone, except for the Headmaster, Mayuri, Nemu, and the soul reapers, and asked in an accusing tone, "How did you know about this, girl?"

Mayuri sneered, "I don't have to share anything with a simple minded idiot like you!"

Before Moody could say anything else, Professor McGonagall interrupted, "Mr. Urahara said there was eight of these Horcruxes and I see only three items here and four black dots on there. Where is the eighth?"

Moody looked extremely smug and questioned, "Yes, good point. Where is the eighth Horcrux? It seems that you have messed up."

Mayuri looked bored as she stated, "Well, it seems that someone has a bit of a higher IQ than most. The eighth Horcrux was in a living host, but it has been dealt with already."

When she had revealed this information, everyone paled, but from the expressions on the Headmaster's and Kisuke's faces, they knew who that living host had been.

**AN: Sorry about taking so long to write this chapter. It took me a long time to come up with this. I hope that you all enjoy this chapter. Please write a review and tell me what you all think of it. Have a wonderful day, everyone.**


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